GliderMan,
As others have pointed out, if you're going for the 24 Hours then you MUST read the AIC and get a slot.
As to the route, every time I've been (from Wycombe), we've routed via Goodwood VOR, SITET*, and the Le Harve NDB for the channel crossing. If the danger areas aren't active then you can miss out SITET and go direct to LHO (or even DVL). The advantage of going this way is that the Goodwood VOR/DME has very good range, and you should be able (depending on altitude) to get a signal almost all the way to the French coast.
From LHO the route is DVL, LGL, LE Mans (as far as I can remember without any charts to hand). Unless the French have upgraded the DVL and LGL VORs since I was there last (in 2002 for the Le Mans Classic), then neither have a DME (most VORs in France don't have a co-located DME).
If you want to get to the town from the circuit, then there's a bus service from just outside the entrance to the circuit which runs regularly while the race is on.
As for camping at the airfield being quieter, don't bet on it. Last time I was there for the 24 Hours (in 1999) it was VERY noisy on the Friday night (the parties went on until at least 3am) and someone was setting of rockets accross the camp site in the early hours as well. Not so bad on the Saturday night as nearly everybody is over at the track.
Brooklands
*SITET - Useful airways reporting point on the FIR, just east of the danger area, I think its marked on the UK CAA charts